2003 northstar misfire

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Northstar Engines and System Technical Discussion Discussion, 2003 northstar misfire in Cadillac Engine Discussion; hello, Need help,i have a 2003 seville sls with approx. 140,000 miles on the clock problem is i have a ...
  1. #1
    gregandcarol is offline Cadillac Owners Member
    Automobile(s): 2003 seville sls
    Join Date
    Feb 2010

    2003 northstar misfire

    Need help,i have a 2003 seville sls with approx. 140,000 miles on the clock problem is i have a service engine light on and blinking.Had it to auto zone to read code it came up #4 cylinder misfire.Pulled plug soaked with fuel no spark.Replaced plug/coil boot and new spark plug started car, again rough idle pulled plug again still wet with fuel.What next???
    Thanks for any info.

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  3. #2
    97EldoCoupe's Avatar
    97EldoCoupe is offline U.S. Patent #8,740,532 - www.studkit.com
    Automobile(s): 97 ETC, 99 Deville, 04 GXP, 06 DTS, 05 SRX, 2010 Sierra SLT
    Join Date
    Mar 2007
    London, Ontario and Altona, MB

    Re: 2003 northstar misfire

    So sorry for the shipping mix-up Greg - when you get that coil swap that in place, it should solve your problem. If it doesn't it'll be the injector flooding the engine. I was told that was a perfect running engine I removed that coil cassette from (I bought it from another forum member - ponyboyt) so if it works good for you, please pay for it as we discussed, if it doesn't, throw it out and buy a new one. These coils do, on occasion, fail- as with all cars. The problem with these is if one coil fails, the whole cassette needs to be replaced....

  4. #3
    NHRATA01 is offline Cadillac Owners Fanatic
    Automobile(s): '12 Regal GS, '01 Trans Am
    Join Date
    Jan 2008
    New York

    Re: 2003 northstar misfire

    Had a coil go bad on mine at just over 50k miles a few months ago, most likely that is it. Unfortunately it necessitates the whole cassette replacement at a cost of ~$230 from GMPartsdirect.com.

    If that isn't it, then it's the injector.

  5. #4
    Submariner409's Avatar
    Submariner409 is offline If it won't run, install big wheels !
    Automobile(s): 2002.5 F55 STS, 2014 Explorer XLT 4WD
    Join Date
    Feb 2006
    MD Eastern Shore

    Re: 2003 northstar misfire

    www.rockauto.com may have some OEM DELPHI coil cassettes for your car with ICM for less than $200 apiece. (The 2 cassettes are identical except for color, so at 6:26 EST it looks like you have 5 choices tonight - with ICM those are a steal...........)

    Don't forget to check the coil-plug connector boots and cassette ground spring also.

  6. #5
    caddydaddy's Avatar
    caddydaddy is offline Cadillac Owners Connoisseur
    Automobile(s): 2005 Escalade 6.0L 2WD, 2007 Jeep Grand Cherokee Limited CRD
    Join Date
    Jan 2003
    Gales Ferry, CT

    Re: 2003 northstar misfire

    I had the front coil cassette fail on my 2000 STS a few months ago with 110k miles. Rock Auto had the best prices on them!

  7. #6
    hundojoe's Avatar
    hundojoe is offline Cadillac Owners Member
    Automobile(s): 2003 Seville SLS, 1999 Silverado
    Join Date
    Nov 2009

    Re: 2003 northstar misfire

    Had a similar type misfire on my 2003 sls, found some white chalkey type corrosion under the coil pack where the springs touch the electric contacts, cleaned it up and problem went away. Also make sure you use some dielectric grease on the contacts when your putting it back together.

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